Intraoperative isovolemic hemodilution technique can be indicated in emergency cases such as in patients expected to undergo urgent neurosurgery. However, acute hemodilution is associated with a risk of increased intracranial pressure, given that the brain appears to be favored at the expense of the splanchnic organs in the resulting redistributrion of cardiac output.1) The aim of the present study was to evaluate the ICP, CaBF, CCBF and CMBF, responses to hyperventilation combined with isovolemic hemodilution in dogs. These results indicate that anesthesiologists should be well in the aggressive use of acute isovolemic hemodilution in patients so as to avoid an increase in cerebral blood flow.2) The aim of the present study was to evalute the hemodynamic and cerebral variables, in the responses to isoflurane induced hypotension combined with isovolemic hemodilution in dogs. These results indicate that, when combined with hemodilution, isoflurane acted as a hypotensive agent, at least regarding the cerebral variables.3) The aim of the present study was to evalute the hemodynamic and cerebral variables in responses to sevoflurane-induced hypotension combined with isovolemic hemodilution in dogs. These results indicate that anathesiologists should be attentive to cerebral variables when formed hypotension is induced by sevoflurane in patient undergoing neurosurgery. Similarly it involves using acute normovolemic hemodilution.4) The objective of this study was to evaluate systemic hemodynamic and cerebral responses dig isovolemic hemodilution alone and when combined with TNG- or PGE1-inducd hypotension in isoflurane anesthetized dogs. These results suggest that hypotensive anesthesia using PGE1 is more effective than TNG under hemodilution conditions, due to the improvement of myocardial contractile force and cerebral oxygen tension.